Art or process of making phosphoric acid.



N0= 669,27l. Patented Mar. 5, l90l.

F. P. VAN DENBERGH.

ART 0R PROCESS OF M G PHUSPHOBIC ACID.

(Application file r. 20, 1896.)

(No Iodol.)

UNI-TED STAT-Es- PATENT OFFICE.

FRANK VAN DENBERGH, OF BUFFALO, NEW'YORK.

ART oR PROCESS OF MAKING PHos HomcrAcm.

SPECIFICATION forming part Of Letters P817912? N0. 669,271, dated March5, 1901.

Application filed April 20, 1896- Serial No. 588,870. (No specimens.) 7

To all whom it may concern.-

Be it known that I, FRANK P. VAN DEN- BEBGH, a citizen of the UnitedStates, residing at Buffalo, New York, have invented certain new anduseful Improvements in the Art or Process of Making Phosphoric Acid; andI do hereby declare the following to be a full, clear, and exactdescription of the invention,

- such as will enable those skilled in the art to mittent.

In order to the better distinguish my process from that heretoforeusually employed,

1 I will now refer to the common manner of manufacturing phosphoricacid. In such manufacture it is customary to digest the ashes of boneswith crude sulfuric acid for several days, separate the calcium. sulfateformed by pressure filtration, concentrate the liquid acid byevaporation to a syrup, treat it with concentrated sulfuric acid, evapcrate, and finally ignite it to rempve the sul-,

furic acid. The ashes of bones are sometimes replaced by the mineralphosphates, and hydrochloric acid is sometimesused instead of sulfuricacid; but by any of these or similar methods the action isslow,'imperfect, and expensive. Moreover, the product made by any ofthese processes contains sulfuric acid, magnesia, arsenic, or otherimpurities, and as phosphoric acid is largely usedin pharmacy andmedicine additional time and expense are necessary in order to removethese impurities. Chemically pure phosphoric acid is prepared fromelementary phosphorus by a slow oxidation in moist air or in shallowvessels containing a small amount of water. This, however, is tedious,expensive, and dangerous -to; the operatives.

My invention has for its object to utilize an abundant raw materialhaving at present but little value in the industrial arts, to avoid thedanger and to lessen the time and cost of producing phosphoric acid, andat the same time to render unnecessary the purification of the acid formany purposes where now suchpurification is absolutely essential.

In carrying out my invention instead of re-' acting upon bone-ashes orother phosphatic material with sulfuric or hydrochloric acid, and thusby slowand expensive processobtaim ing an impure phosphoric acid, Iemploy heat and electrolysis, both derived from an electric currentwithin a furnace, and operate with these forces directly upon andthrough the apatite or other phosphorus-containing material. a Inpractice I prefer that such phosphorus containing material should bemixed with sand, gravel, quartz, cullet, clay, feldspar, shale, or othersilicious material, which will serve as a flux, in order that there maybe a molten mass or bath within the furnace of relatively easily-fusedmaterials, and that the current of electricity should pass through thisbath and the electrolysis should take place therein.

The atmosphere within the furnace should containan excess of freeoxygen, which may be supplied from hematite iron ore or otheroxygen-yielding solid, which may be introduced into the furnace with theother solid materials, or from steam, air, oxygen, ozone,

or other oxygen-yielding gas which may be injected into the furnacel IIn carrying out my invention the apatite orother phosphorus-containingmaterial and the other solid materials which may be employed are firstcrushed or broken into small pieces in order to facilitate feeding theminto the furnace and their subsequent fusion therein. The siliciousmaterials are firstfused by the heat of the electric current and form amolten bath, and the electric current passing into and through this bathoperates by electrolysis to decompose the phosphorus-containingmaterial, liberating phosphorus, and this being set free in anatmosphere containing an excess of free oxygen there are formedphosphorus oxids,'principally the peutoxid,

(F 0 which oxids are afterward hydrated, thereby forming phosphoricacid. This acid is led off, condensed, cooled, and collected by means ofsuitable apparatus.

' To insure the hydration of the phosphorus oxids, I prefer to introducesteam or vapor of water into the furnace-chamber.

The electric furnace employed may be of any desired type, provided ithas a properlyclosed chamber and a proper exit for the va-- pors whichare formed within the furnacechamber, such exit connecting with acondensing apparatus.- It is especially advan tageous, however, to use afurnace aflfording a continuous process of reduction. In the drawingaccompanying this case I have illus trated in central transverse sectionan electric furnace adapted to the carrying out of my invention, alldetails of construction and arrangement being omitted in so far aspermissible with a showing of an apparatus sufficient for a clear.understanding of my process. Referring to such drawing, 2 2 repre= sentfeed-passages through which the mate.

erated within the furnace-chamber are dis charged through an opening 7into a trunk or conduit 8, which is connected with a condensingapparatus,the latter not being shown 9 9 are openings into the trunk orconduit 8, through which steam may be introduced into the latter, thesteam being supplied from a pipe 10. It is in this trunk, chamber, orconduit 8 that the main portion of the hydration of the oxid vapors fromthe furnace takesplace, the steam or water vapor supplied through theapertures 9 supplying the elements for such hydration.

11 11 indicate steam-pipes connected with Y openings or passages12,-leading into the body of the furnace. Through these vapor or wa: termay be discharged directly into'the'furnace-chamber when conditionsrequire that this should be done.' l

. The material is introducedin to the furnace and being brought withinthe direct influence of the electric current it is rapidly fused. Theexact amount or proportion of the flux which may be used cannot bestated arbitrarily, owing to the variation in the character and richnessof the phosphorus-containing. ma: terial and must. in each case berelatively determined, as it may be by any person skilled in the art ofsmelting ores. The quantity of steam must in like manner be determinedby the quality of the solid materials and the vol- 1 ume of suchmaterials being used in the proc- 'ess.

The volume and quality of the electric current employed will also bedetermined by the work done and by the character of the material beingtreated.

The method and means which I employ for condensing the vapors are notessentially different from those commonly employed, and

I may use any successful system. I prefer,

however,to conduct the vapors through tubes of acid-resisting material,which are submerged in rapidly-flowing cold water before dischargingthem into a condensing-chamber for the economy afforded thereby. I donot, however, restrict or limit my in vention to the particular meansdescribed for carrying out the process, as any one and all of them maybe varied without'departing from the spirit of my invention, andI do notlimit myself to the use of steam or watervapor as an oxidiz= ing agent,but claim the right to use oxygen or air, ozone, hematite iron ore, orother suitable material capable of yielding a large proportion of oxygenwhen subjected to the heat and energy of the electric current within thefurnace, and these oxygen-yielding materials may be heated separatelyfrom the phosphorus-yielding materials, as is sometimes desirable, inorder that' a part of the phosphor'us-may not be lost by its combinationwith the other materialssuch, for instance, as iron, when hematite ironore is used as the oxygen-supplying m aterialL Having thus described myinvention, what I claim, and desire to secure by Letters Patent, is-

1. In the manufacture of phosphoric acid, the herein-described process,which consists in subjecting a phosphorus-containing substance and asilicious substance to heat and electrolysis until a silicate is formed,and substantially all of the phosphorus has been driven off or set free,and combining the phosphorus with oxygen and hydrogen to form phosphoricacid, substantially as set forth.

. 2. In the manufacture of phosphoric acid, the herein-describedprocess, which consists in subjecting a phosphorus-containing substanceand a silicious substance to heat, and electrolysis derived from anelectric current, in an atmosphere containing an excess of oxygen, untila silicate is formed, and substantially all of the phosphorus has beendriven off or set free, whereby phosphorus oxids are formed, andsubsequently hydrating these oxids to form phosphoric acid,substantially as set forth. p

3. In the manufacture of phosphoric acid, the herein-described process,which consists in subjecting a native phosphate to heat andelectrolysis, both derived from an electric on rrent applied to thephosphate until substantially all of the phosphorus has been driven 0Eor set free, and combining the phosphorus with hydrogen and oxygen toform phosphoric acid, substantially as set forth.

4. In the manufacture of phosphoric acid, the herein-described process,which consists in subjecting a phosphorus-containing substance aud asilicious substance to heat and electrolysis, both derived from anelectric current applied within a furnace, and directly to the materialwhile in a molten condition, and in the presence of aifibxcess' ofoxygen until a silicate is formed, and substantially all of thephosphorus has been driven olf or set free,

IIO

oee,271' r and combining such phosphorus with oxygen phorus, andinjecting steam into the phospho-- and hydrogen to form phosphoricacidQs'nbronsoxidswhich have been formedvto produce v *st antially asset forth. phosphoric acid, substantially as set forth;

' 5. In the manufacture of phosphoric acid, In testimonythat I claim theinvention 15 5 the'hereiue'described process, which consists aboireesetforth I affix my signature in pr'es-. in subjecting a,phosphorus-containing subence of two witnesses. '-.stance and asilicious substance to'hea't and 1 electrolysis-derived from an elecriccurrent, I 'B RANK VAN D and applied-to the substance'being' treated.Witnesses: to until substantially all of the phosphorus has THOMAS D.MAGNOE,

. I been driven off or set free, oxidizing the phos- FRANK T.. HAGQERTY.

